Such sensor systems are used for monitoring the correct function of control surfaces, in particular, on the wings of an aircraft. For influencing the lift and drag coefficients of the wings, airplanes are equipped with control surfaces such as slats and landing flaps, which change the aerodynamic properties of the wings such that for starting and landing the aircraft has slow-flying properties, whereas in cruise flight the desired fast-flying properties are achieved by correspondingly positioning the control surfaces such as the slats and landing flaps.
Malfunctions in the drive system of these control surfaces can lead to the so-called skewing, misalignment or loss of individual control surface segments, whereby the aerodynamic properties of the wings are impaired in an undesired way. In particular, undesired rolling or yawing moments or also consequential damages can occur upon loss of individual control surface segments.
To detect such malfunctions in good time and stop the course of the damage, sensor systems are known, which should detect skewing or asynchronism or the loss of individual control surface segments in good time. If an error is detected, a signal is generated, which leads to the stop of the drive system and provides a corresponding warning signal to the cockpit crew.
From U.S. Pat. No. 4,686,907, a sensor system is known in which marks are arranged on a bent track, which is guided in guide rollers and upon movement causes an arc-shaped movement of the flap body. During a movement of the track, these marks move past laterally arranged sensors and thus generate signals, by means of which the position of the flap can be detected. This system has a variety of applications, but requires a large number of sensors.
From U.S. Pat. No. 5,680,124, there is furthermore known a sensor system in which a Bowden line is arranged within a row of flap bodies of a wing, which are located one beside the other. The ends of the Bowden line are attached to the first and to the last flap body, so that the length of this Bowden line remains constant when all flaps move in synchronism. On the other hand, an asynchronous movement of adjacent flaps increases the length of the Bowden line, which is detected by a corresponding sensor. However, this system only can detect an asynchronous movement of adjacent flaps, whereas a disturbed movement of the inner and outer flap ends is not detected. Monitoring an individual flap neither is possible with this arrangement.
In addition, the wings of modern passenger airplanes frequently have a wing depth which is decreasing from the inside to the outside (tapered wings), which often results in different travel distance distances in terms of span for landing flaps and slats, i.e. the inboard flaps have a greater travel distance distances than the outboard flaps. There are also arrangements which require different travel distance distances of the drive stations of a single flap. Such differences of the desired travel distance distances of the flaps can, however, not be taken into account by known sensor systems, or only with great effort.
Therefore, it is the object of the present invention to provide a sensor system for monitoring the synchronism of control surfaces of an aircraft, which can be used for a variety of applications with little constructive effort and in particular also can account for different desired travel distance distances of the control surfaces. Furthermore, a safe and reliable monitoring of synchronism should be possible, wherein in particular a self-monitoring construction is desired.
In accordance with the invention, this object is solved by a sensor system according to the present invention. Such sensor system for monitoring the synchronism of control surfaces of an aircraft comprises two transmission links for the mechanical transmission of the movement of one or more control surfaces to at least one sensor, wherein the two transmission links are coupled with each other mechanically and/or via the at least one sensor, whereby a difference between the movements transmitted by the transmission links can be monitored. By using two mechanical transmission links it is possible to monitor the synchronism of one or more control surfaces in a safe and simple way by monitoring the difference between the movements transmitted by the transmission links. To provide for this difference measurement, the two transmission links are coupled with each other mechanically and/or via the at least one sensor, so that a constructively simple and yet reliable monitoring becomes possible. In particular, a multitude of sensors thus can be omitted. Furthermore, the system is self-monitoring, since a breakage of one of the two transmission links is detected as an error.
The mechanical transmission links can transmit the movement of individual or several regions of a single control surface, so that e.g. the travel distance distance of a control surface in the left-hand region can be compared with the travel distance distance of the same control surface in the right-hand region. Alternatively, the two transmission links also can engage different control surfaces, so that the synchronism of two control surfaces can be monitored.
Advantageously, coupling the transmission links is effected via one or more rotatively movable coupling elements. By converting the translational movement of the control surfaces into a rotational movement, monitoring the difference between the movements transmitted by the transmission links is simplified considerably, wherein the rotatively movable coupling elements also require only little packaging space.
Furthermore advantageously, different desired travel distance distances are compensated in accordance with the invention by corresponding different transmission ratios of the movements transmitted by the transmission links to one or more coupling elements. Thus, if the control surfaces have different desired travel distance distances on different points of one or more control surfaces due to the decreasing wing depth described above, this can be taken into account in that the movements transmitted from these points of the control surfaces by the transmission links are transmitted to the coupling element(s) with different transmission ratios. By corresponding adjustment of the transmission ratios, the desired travel distance distance difference, which occurs with an error-free movement of the control flaps, can be taken into account automatically. By means of the different transmission ratios it thus can be ensured that the difference monitored by the sensor is zero in the trouble-free case and only differs from zero in the case of a malfunction. This provides for an easy adaptation of the sensor system of the invention to all kinds of tasks and control flaps in a purely mechanical way. In particular, complicated evaluation electronics thus can be omitted, since the compensation of the different travel distances can only be achieved mechanically.
Furthermore advantageously, the two transmission links in the sensor system of the invention engage two coupling elements movable against each other, whose relative movement is monitored by a sensor. As a result, only one sensor must be used, which monitors the synchronism. Deviations from the desired travel distance of the control surfaces lead to a relative movement between the two coupling elements movable against each other, which can be detected safely and easily.
Alternatively, the two transmission links also can engage an inherently rigid coupling element, wherein two sensors are provided, which monitor the forces transmitted by the transmission links. In the case of a trouble-free movement of the control surfaces, the two transmission links move the common coupling element in the same way, so that constant forces are acting here. In the case of an asynchronous movement, however, at least one of the transmission links is loaded with higher or lower forces, which then are detected by the sensors.
In an advantageous embodiment of the sensor system of the invention, the two transmission links each comprise a Bowden line. The same advantageously is arranged such that in the case of a movement of the control surface or control surfaces, the length of the Bowden line is changed. By means of such Bowden lines, a multitude of sensor arrangements can be realized, which can monitor the travel distances of both one and several control surfaces.
Advantageously, the cables of the two Bowden lines are reeled up on one or more drums on at least one end. When the length of the Bowden line path is increased or reduced by a movement of the control surface or control surfaces, the cables accordingly are reeled off from the drum or reeled up onto the drum. The drum or drums advantageously are arranged on the wing structure, so that the Bowden line path is changed in its length in the case of a change in position of the control surfaces with respect to the wing structure. For this purpose, the cables either each are attached to a control surface with their other end or extend along the control surface or control surfaces via deflection pulleys, before they are attached to the wing structure at some other point. Hence it is possible to realize a multitude of different possibilities for monitoring the position of the control surfaces.
Advantageously, the Bowden lines are tensioned by one or more return springs of the one or more drums. The return springs thus ensure that the cables of the Bowden lines are again reeled up onto the drums, when the length of the Bowden line path is reduced by a movement of a control surface. In the case of a breakage of the cable, this also leads to a response of the sensor, so that a self-monitoring system is created.
In accordance with the invention, the cables of the two Bowden lines advantageously are reeled up on the drums in opposite directions. By such winding of the cables in opposite directions it is achieved that the change in length of the Bowden lines is effected in the same way during a rotation of the drum or drums, i.e. that either both Bowden lines become longer or both Bowden lines become shorter. This results in an easy monitoring of the difference of the movements transmitted by the two Bowden lines.
Furthermore advantageously, the cables of the two Bowden lines are reeled up onto drums or drum regions with a different diameter. By means of drums or drum regions with a different diameter, a different conversion of the longitudinal movement transmitted by the Bowden lines into a rotational movement of the drums can be achieved, so that different desired travel distances can be compensated. Due to the different diameters, there is thus obtained a particularly simple mechanical possibility for taking into account different travel distances. In particular, complicated evaluation electronics can be omitted, since the compensation of the different travel distances can be achieved by the different diameters alone.
In an advantageous embodiment, the cables of the two Bowden lines are reeled up onto a common drum, wherein cable force sensors are integrated in the cables. The common drum thus ensures a mechanical coupling of the Bowden lines, in which in the case of a proper synchronous movement of the control surfaces the two cables are in an equilibrium of forces with the return spring of the drum and are uniformly loaded by the same. In the case of an asynchronous movement, however, one of the two cable force sensors is loaded less or more, whereby the error then can be detected. Advantageously, an error is detected via a lower load.
Advantageously, the cable force sensors include a spring and a sensor which monitors a change in length of the spring. In trouble-free operation, the spring of the cable force sensor has a certain length which results from the equilibrium of forces with the return spring of the drum. In the case of a lower or higher load of the spring of the cable force sensor, however, the spring becomes shorter or longer, which is detected by the sensor. Advantageously, an error is detected by the spring becoming shorter.
Alternatively, the two Bowden lines advantageously can also be reeled up on two separate drums, wherein the sensor monitors a difference in angle between the drums. With only one sensor, synchronism can easily be monitored here. In the case of synchronism, the two drums move in the same way, whereas in the case of an error, a difference in angle occurs between the movement of the two drums, which is detected by the sensor.
Advantageously, the drums are coaxially arranged one beside the other. This provides simple possibilities for monitoring the difference in angle between the two drums. For instance, the drums can be configured as a spindle-nut unit, so that a different rotation of the drum results in a lifting movement, which actuates a sensor. The sensor unit can also be e.g. an inductive proximity sensor, which is mounted on the side of the structure and by means of marks, so-called targets, on the periphery of the drums incrementally detects the synchronous movement of the drum by pulse width measurement. In a further advantageous configuration of the sensor unit, e.g. a proximity sensor can be arranged on the one drum, which detects marks on the opposed second drum. In the case of a synchronous movement, a permanent “target-near” signal thus is obtained, which is interrupted in a case of error.
In a further advantageous embodiment of the sensor system of the invention, the transmission links transmit a rotational movement, in particular via a revolving tube or a flexible shaft. This provides a mechanically simple possibility for transmitting the movement of the control surfaces to the sensor. For instance, the revolving tube or the flexible shaft can transmit the movement of a control surface element via a toothed rack or gear wheel arrangement.
Advantageously, the sensor monitors a difference in angle between the rotational movements transmitted by the transmission links. Similar to the configuration with two separate drums, an asynchronism in the movements transmitted by the two transmission links thus can easily be detected.
To compensate different desired travel distances, transmissions with different gear ratios advantageously are provided in the two transmission links. This also provides a simple mechanical possibility for adapting the sensor system of the invention to different travel distances.
The sensor system of the invention can be used in a multitude of control surface arrangements, wherein the synchronism of different elements can be checked by the difference measurement in accordance with the invention.
Thus, the transmission links can transmit the movements of a single control surface taking place at different points. In this way, it can be checked for instance whether the one side of a control surface is moved in synchronism with the other side of the control surface. In particular when a plurality of drives are provided for moving a control surface, the proper operation of the drives can be checked in this way.
Alternatively, the transmission links transmit the movements of at least two different control surfaces, in particular of at least two symmetrically moved control surfaces. In this way, for instance, the synchronism of two control surfaces arranged symmetrically with respect to the longitudinal axis of the aircraft on both wings can be monitored.
Furthermore advantageously, each transmission link also can transmit the movement of a plurality of control surfaces. This can be done in particular in that a Bowden line of the invention is drawn through a plurality of control surfaces, so that asynchronous movements of the control surfaces likewise can be monitored.